1. Field of the Invention
The present invention relates generally to insulator layers formed within integrated circuits. More particularly, the present invention relates to silicon oxide insulator spacer layers selectively deposited within patterned metal conductor layers within integrated circuits.
2. Description of the Related Art
Integrated circuits are typically fabricated from semiconductor substrates upon whose surfaces are formed a multiplicity of active semiconductor regions. Within those active semiconductor regions are formed transistors, resistors, diodes and other electrical circuit elements. Those electrical circuit elements are interconnected internally and externally to the semiconductor substrates upon which they are formed through the use of conductor metal layers which are separated by insulator layers.
In accord with the continuing evolutionary trend in semiconductor technology, conductor metal line-widths and spacings within advanced semiconductor integrated circuits have continued to decrease while aspect ratios of those conductor metal lines have continued to increase. As a result of these factors, it is frequently desirable in advanced semiconductor integrated circuits to develop methods and materials through which there may be formed between adjoining patterned conductor metal layers insulator spacer layers which possess excellent gap filling and planarizing properties. Insulator spacer layers which possess excellent gap filling and planarizing properties are most likely to provide void free insulator spacer layers which provide superior substrates for over-lying insulator layers which may provide additional gap- filling and planarizing properties.
It is towards the goal of developing silicon oxide insulator spacer layers which possess excellent gap filling and planarizing properties that the present invention is directed.
Methods by which there may be formed upon semiconductor substrates various types of layers which have specific growth properties, such as gap filling and planarizing properties, are known in the art. For example, Verma in U.S. Pat. No. 4,717,687 describes a method for growing thermal oxides at different rates upon different portions of a semiconductor substrate. The method derives from different growth rates for thermal oxides grown from crystalline silicon semiconductor substrate regions in comparison with thermal oxides grown from metastable amorphous silicon semiconductor substrate regions.
In addition, Yu in U.S. Pat. No. 5,302,555 discloses a method for preferentially depositing a silicon oxide coating on horizontal surfaces of structured semiconductor substrates. The method involves control of several parameters related to the gaseous reactant mixture from which is deposited the silicon oxide coating and several additional parameters related to design of the reactor within which is deposited the silicon oxide coating. Significant parameters which are controlled include the flow ratio of reactant gases, the reactor pressure and the geometry of the susceptor within the reactor.
Still further, Wang et al., in U.S. Pat. Nos. 4,872,947 and 5,354,715, and E. J. Korczyski et al., in "Improved Sub-Micron Inter-Metal Dielectric Gap-Filling TEOS/Ozone APCVD," Microelectronics Tech., January 1992, pp. 22-27, describe process methods and process hardware for forming planarizing silicon oxide insulating layers through an ozone assisted Chemical Vapor Deposition (CVD) process employing Tetra Ethyl Ortho Silicate (TEOS) as the silicon source material.
Most pertinent to the present invention, however, is the disclosure of Hieber et al. in U.S. Pat. No. 5,399,389. Hieber discloses a method for locally and globally planarizing a structured semiconductor substrate with a silicon oxide layer formed through an ozone activated Chemical Vapor Deposition (CVD) process. The method employs a structured semiconductor substrate fabricated from materials at the lower levels of the structure which have inherently increased growth rates for silicon oxide layers formed through an ozone activated Chemical Vapor Deposition (CVD) process. The method preferably employs a Boro Phospho Silicate Glass (BPSG) or a Phospho Silicate Glass (PSG) lower layer. Optionally, the method also employs a Plasma Enhanced Chemical Vapor Deposited (PECVD) silicon oxide upper layer to retard growth upon metallization layers which otherwise typically form upper layers of the structured semiconductor substrate.
Desirable in the art are methods and materials which expand from the Hiebert disclosure and yield silicon oxide insulator spacer layers which provide a superior substrate for overlying silicon oxide insulator layers, such as over-lying gap filling and planarizing silicon oxide insulating layers, within advanced integrated circuits. Most desirable are silicon oxide insulator spacer layers which may be formed selectively between adjoining patterned metal layers within an advanced integrated circuit and not upon the top surfaces of those adjoining patterned metal layers. Such selectively deposited silicon oxide insulator spacer layers would avoid the need for substantial additional processing, such as etchback processing and sputtering processing, to remove thick portions of silicon oxide insulator spacer layers formed upon surfaces of those adjoining patterned metal layers.